The present invention relates generally to an addressing machine in a mass mailing system and, more particularly, to a locking mechanism for locking a print head assembly in the addressing machine.
In a mass mailing system, an addressing machine having a plurality of print heads is typically used to print a mailing address on an envelope along with other printed items, such as the postage indicia, return address and promotional messages. Because the size of the envelope may vary, the print head in the addressing machine must be adjusted. Typically, the print heads are mounted on one or more shafts so that the position of the print heads can be adjusted along the longitudinal axis of the shaft, which is substantially perpendicular to the moving direction of the envelope.
As shown in FIG. 1, the addressing machine 1 comprises an envelope feeder 10 and a printing section 100. The envelope feeder 10 has a driving mechanism 16 for releasing one envelope 14 at a time from a stack 12 to the printing section 100. The printing section 100 has a driving mechanism 20 and a pair of pickup rollers 22 to move the released envelope 14 further along the moving direction 90. While the envelope 14 is moving along the moving direction 90, a plurality of print head assemblies 40 is used to print the printed items on the envelope 14.
A top view of the printing section 100 is shown in FIG. 2. As shown, the printing section 100 has a rack 200 for mounting a plurality of shaft mounts 210. The print head assemblies are mounted on a plurality of shafts 220, which are mounted on the shaft mounts 210. In order to adjust the print head assemblies 40 relative to the moving path 92 of the envelope 14, the print head assemblies 40 can be slid on the shafts 220. Once each of the print head assemblies 40 has been moved to a desired position, it is locked in that position so that the printed items on the envelope 40 can be printed in a designated area in a consistent fashion. Advantageously, the print head assembly 40 comprises a plurality of print heads fixedly mounted on a carriage 50, which is slideably mounted on the shaft 220.
Furthermore, a machine operator should be able to rotate the print head assemblies 40 upward, as shown in FIG. 3, to occasionally clean the print heads on the assemblies.
Thus, it is desirable and advantageous to provide a method and device for locking and unlocking the print head assemblies so that the position of the print head assemblies relative to the moving path of the envelope can be easily changed or adjusted. Furthermore, it is desirable and advantageous to have a reasonably small locking mechanism so that it will not interfere with the operator when the operator adjusts the position of the print head assemblies and when the operator lifts the print head assemblies for cleaning or other maintenance purposes.
It is a primary objective to the present invention to provide a method and mechanism for locking and unlocking a device for engagingly connecting a carriage to a shaft, such that when the device is unlocked, the carriage position along the shaft can be adjusted, and when the device is locked, the adjusted position is maintained. This objective can be achieved by engaging a collet having a tapered male pipe thread section with a flange having a matching female pipe thread section. The collet is fixedly attached to a thumb wheel or turn knob so that when the thumb wheel is turned to tighten the collet further into the flange, the collet is squeezed against the shaft, thereby restricting the collet, together with the flange, from moving along the longitudinal axis of the shaft. But when the thumb wheel is turned the other direction to loosen the collet from the flange, the collet and the flange can be slid along the shaft. As such, when the carriage is fixedly attached to the flange, its position can be adjusted or locked.
Thus, according to the first aspect of the present invention, there is provided a locking device for use in conjunction with a shaft, the locking device connected to a carriage, the shaft having a longitudinal axis, the locking device operable in an unlock position and a locked position. The locking device comprises:
a collet having
a first end and a second end along the longitudinal axis of the shaft,
an inner circumference for slideably mounting on the shaft, and
an outer surface having a first threaded section adjacent to the first end and a second threaded section adjacent to the second end;
means for connecting the locking device to the carriage; and
a flange having a substantially circular opening with a threaded circumference for rotatably mounting over the outer surface of the collet, wherein the diameter of the circular opening is greater than at least a part of the first threaded section of the collet, and smaller than the diameter of at least a part of the second threaded section of collet, such that
the locking device is in the locked position when the threaded circumference of the flange is engaged with the second threaded section of the collet, the flange causing the inner circumference of the collet to exert a frictional force against a section of the shaft, restricting the locking device and the carriage from moving along the longitudinal axis of the shaft, and
the locking device is in the unlocked position when the threaded circumference of the flange is engaged with the first threaded section of the collet, the flange reducing the exerted frictional force against the shaft, allowing the locking device and the carriage to move along the longitudinal axis of the shaft.
The locking device further comprises a knob attached to the second end of the collet for turning the collet
in a rotational direction about the longitudinal axis of the shaft to change the locking device from the locked position to the unlocked position, or
in an opposite direction to change the locking device from the unlocked position to the locked position.
Preferably, the collet further includes a plurality of slits extending from the first end of the collet to at least part of the second threaded section, dividing at least a part of the collet into a plurality of circumferential sections, such that when the threaded circumference of the flange is engaged with the first threaded section of the collet in the unlocked position, the flange urges the circumferential sections to move toward the shaft for exerting the frictional force.
The carriage is used for mounting a print head assembly for printing a mailpiece moving in a moving path, and wherein the threaded circumference of the flange can be caused to engage with the first threaded section of the collet for adjusting the position of the print head assembly relative to the moving path based on the mailpiece, and the threaded circumference can be caused to engage with the second threaded section of the collet for maintaining the adjusted position of the print head assembly.
Advantageously, the collet has a coaxially extended section, the extended section having
an outer circumference smaller than the diameter of the circular opening so as to allow the flange to be engaged with the threaded sections through the extended section, and
an inner circumference substantially equal to the inner circumference of the collet such that when the threaded circumference of the flange is engaged with the second threaded section of the collet, the inner circumference of the extended section also exerts a frictional force against the shaft.
The flange is fixedly attached to the connecting means.
According to the second aspect of the present invention, there is provided a method for locking and unlocking a carriage engagingly connected to a shaft having a longitudinal axis. The method comprises the steps of:
1) providing a locking device, slideably mounting on the shaft, the locking device comprising:
a collet having
a first end and a second end along the longitudinal axis of the shaft,
an inner circumference for slideably amounted on the shaft, and
an outer surface having a first threaded section adjacent to the first end and a second threaded section adjacent to the second end;
means for connecting the locking device to the carriage; and
a flange having a substantially circular opening with a threaded circumference for rotatably mounting over the outer surface of the collet, wherein the diameter of the circular opening is greater than at least a part of the first threaded section of the collet, and smaller than the diameter of at least a part of the second threaded section of collet, such that
when the threaded circumference of the flange is engaged with the second threaded section of the collet, the flange causes the inner circumference of the collet to exert a frictional force against a section of the shaft, thereby restricting the locking device from moving along the longitudinal axis of the shaft, and
when the threaded circumference of the flange is engaged with the first threaded section of the collet, the flange reduces said frictional force; allowing the locking device to move along the longitudinal axis of the shaft;
2) causing the threaded circumference of the flange to engage with the first threaded section of the collet for adjusting the position of the carriage along the longitudinal axis of the shaft, and
3) causing the threaded circumference of the flange to engage with the second threaded section of the collet for maintaining the adjusted position of the carriage.
The second end of the collet is attached to a knob and wherein the knob can be turned in a rotational direction to cause the threaded circumference of the flange to engage with the second threaded section of the collet, and the knob can be turned in an opposite direction to cause the threaded circumference of the flange to engage with the first threaded section.
The rotational direction is a clockwise direction and the opposition direction is a counter-clockwise direction.
According to the third aspect of the present invention, there is provided an addressing machine having at least one print head assembly for printing a substantially flat item moving in a moving direction. The addressing machine comprising:
at least one shaft having a longitudinal axis, substantially perpendicular to the moving direction of the flat item;
a shaft mount for mounting the shaft; and
a locking device comprising:
a collet having
a first end and a second end along the longitudinal axis of the shaft,
an inner circumference for slideably amounting on the shaft, and
an outer surface having a first threaded section adjacent to the first end and a second threaded section adjacent to the second end;
means for connecting the locking device to the carriage; and
a flange having a substantially circular opening with a threaded circumference for rotatably mounting over the outer surface of the collet, wherein the diameter of the circular opening is greater than at least a part of the first threaded section of the collet, and smaller than the diameter of at least a part of the second threaded section of collet, such that
when the threaded circumference of the flange is engaged with the first threaded section of the collet, the locking device and the carriage can be moved along the longitudinal axis of the shaft for adjusting the position of the print head assembly relative to the moving direction of the flat item, and
when the threaded circumference of the flange is engaged with the second threaded section of the collet in the locked position, the flange causes the inner circumference of the collet to exert a frictional force against a section of the shaft, restricting the locking device and the carriage from moving along the longitudinal axis of the shaft, thereby maintaining the adjusted position of the print head assembly.
The flat item can be an envelope, a sheet of paper or a mailpiece.
The present invention will become apparent upon reading the description taken in conjunction with FIGS. 1 to 7.